<SEC-DOCUMENT>0001104659-19-054991.txt : 20191018
<SEC-HEADER>0001104659-19-054991.hdr.sgml : 20191018
<ACCEPTANCE-DATETIME>20191018164847
ACCESSION NUMBER:		0001104659-19-054991
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20191016
FILED AS OF DATE:		20191018
DATE AS OF CHANGE:		20191018

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kolchinsky Peter
		CENTRAL INDEX KEY:			0001384859

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38223
		FILM NUMBER:		191158225

	MAIL ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA Capital Healthcare Fund LP
		CENTRAL INDEX KEY:			0001315082
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38223
		FILM NUMBER:		191158226

	BUSINESS ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		6177782500

	MAIL ADDRESS:	
		STREET 1:		20 PARK PLAZA, SUITE 1200
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER NAME:	
		FORMER CONFORMED NAME:	RA Capital Biotech Fund LP
		DATE OF NAME CHANGE:	20050121

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA CAPITAL MANAGEMENT, LLC
		CENTRAL INDEX KEY:			0001346824
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38223
		FILM NUMBER:		191158227

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RHYTHM PHARMACEUTICALS, INC.
		CENTRAL INDEX KEY:			0001649904
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				462159271
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		222 BERKELEY STREET
		STREET 2:		12TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		857-264-4280

	MAIL ADDRESS:	
		STREET 1:		222 BERKELEY STREET
		STREET 2:		12TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RHYTHM METABOLIC, INC.
		DATE OF NAME CHANGE:	20150803
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>tm1920573_3.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-10-16</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001649904</issuerCik>
        <issuerName>RHYTHM PHARMACEUTICALS, INC.</issuerName>
        <issuerTradingSymbol>RYTM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001346824</rptOwnerCik>
            <rptOwnerName>RA CAPITAL MANAGEMENT, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001315082</rptOwnerCik>
            <rptOwnerName>RA Capital Healthcare Fund LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001384859</rptOwnerCik>
            <rptOwnerName>Kolchinsky Peter</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5422312</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These securities include 4,599,403 shares held by RA Capital Healthcare Fund, L.P. (the &quot;Fund&quot;) and 822,909 shares held in a separately managed account (the &quot;Account&quot;).</footnote>
        <footnote id="F2">RA Capital Management, LLC (the &quot;Adviser&quot;) is the general partner of the Fund and the investment adviser for the Account. Peter Kolchinsky is the sole manager of the Adviser. The Adviser and Dr. Kolchinsky may be deemed indirect beneficial owners of the securities for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the &quot;Act&quot;). They disclaim beneficial ownership of any of the reported securities for the purpose of determining whether they are subject to Section 16 of the Act, however, in reliance on Rule 16a-1(a)(1)(v) and (vii). To the extent that they might be deemed subject to Section 16, they disclaim beneficial ownership of securities held by the Fund for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein, and disclaim any pecuniary interest in securities held in the Account.</footnote>
        <footnote id="F3">The filing of this Form 3 shall not be construed as an admission that either the Adviser or Dr. Kolchinsky is or was for the purposes of Section 16(a), or otherwise, the beneficial owner of any of the securities held in the Account.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Management, LLC</signatureName>
        <signatureDate>2019-10-18</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Management, LLC, the General Partner of RA Capital Healthcare Fund, L.P.</signatureName>
        <signatureDate>2019-10-18</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, individually</signatureName>
        <signatureDate>2019-10-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
